This invention relates generally to inflatable passive restraint systems for use in vehicles for restraining the movement of a seated occupant such as in the event of a collision. More particularly, the invention relates to an improved attachment arrangement for securing a decorative cover to or within an inflatable occupant restraint airbag module assembly.
It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., "passive restraint systems." Such systems are commonly composed of one or more module assemblies mounted within the passenger compartment of a vehicle. Typical module assemblies used in such systems contain or include an inflatable vehicle occupant restraint, such as in the form of a cushion or bag, commonly referred to as an "airbag cushion." In practice, airbag cushions are normally housed in an uninflated and folded condition to reduce or minimize space requirements. Typically, upon actuation of the system, such as when the vehicle encounters a sudden deceleration as in the event of a collision, an associated airbag cushion is designed to inflate or expand in a matter of no more than a few milliseconds with an inflation fluid, e.g., a gas, produced or supplied by a device commonly referred to as an "inflator." In practice, such an airbag cushion is desirably deployed into a location within the vehicle between the occupant and certain parts of the vehicle interior, such as a door, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such part(s) of the vehicle interior.
In such module assemblies, it is common for the airbag cushion and, at least a portion, of the associated inflator device to be stowed or contained within a module housing such as composed, at least in part, by a housing member such as in the form of a reaction plate or other appropriately selected shape or form. Such housing member components typically have joined or connected therewith an associated or corresponding cover member or element. As will be appreciated, the inclusion of such a cover member can be desirable in various respects. For example, such a cover member may desirably serve to enclose various of the respective module assembly components such as to prevent damage thereto, such as damage to the airbag cushion. Further, it has become common to provide for the inclusion of such a cover member as a decorative feature such as forms a part of the dashboard, steering wheel, seat, door, roof, etc. of the vehicle. Such cover members typically include a frangible section, such as having tear lines of reduced strength such as to permit one or more sections of the cover member to move upon system actuation such as to permit the associated airbag cushion to expand past the cover upon inflation. In practice, the frangible section of such cover members must be sufficiently strong to resist accidental opening prior to proper actuation of the restraint system. Consequently, the frangible sections of such cover members generally require the proper application of a relatively large force onto the cover, such as by the inflating airbag cushion, before the frangible section releases and permits the airbag cushion to deploy therethrough.
The application of such large forces may, however, create a risk that the cover or at least a portion thereof may undesirably become dislodged or unattached from the associated housing member. In order to reduce, minimize or eliminate the risk of such dislodgement or detachment, a need and a demand has existed for a cover attachment arrangement wherein the cover is securely attached to or with the module housing. Unfortunately, the need for strength in the connection between an associated cover and housing has often resulted in more complicated than desired connection schemes. For example, in order to ensure proper cover attachment and retention, common cover and housing connection schemes have incorporated or relied on the inclusion of one or more of the following features:
1) various secondary components, such as rivets or other fasteners or the like; PA1 2) various secondary operations, such as crimping or the like; and PA1 3) relatively intricate or complicated shapes or forms. PA1 1) secondary components, such as rivets or other fasteners or the like; PA1 2) secondary operations, such as crimping or the like; and PA1 3) relatively intricate or complicated shapes or forms. PA1 1) various secondary components, such as rivets or other fasteners or the like; PA1 2) various secondary operations, such as crimping or the like; and PA1 3) relatively intricate or complicated shapes or forms.
Unfortunately, the inclusion of such features typically undesirably increases the costs associated with the connection scheme. Further, the inclusion of such features typically undesirably complicates or makes more expensive the rework of such installations. For example, the rework of such designs is typically laborious and may require scrapping of one or more components involved in the rework.
The problem of complicated connection between a cover and associated housing is at least in part addressed by commonly assigned U.S. Pat. No. 5,588,669, issued Dec. 31, 1996, to Leonard et al., the disclosure of which patent is incorporated herein in its entirety. This patent discloses a hook and window airbag cover attachment arrangement wherein the housing includes a side wall which forms a series of outwardly extending mounting tabs or hooks and the cover includes a series of windows or slots which mate with the outwardly extending hooks.
FIGS. 1 and 2 illustrate a simplified module assembly, designated by the reference numeral 50, utilizing one such common cover and housing connection. More particularly, FIG. 1 is a fragmentary bottom view of the module assembly 50 of complimentary sized and shaped reaction housing 52 and cover 54. As shown, the reaction housing 52 is generally rectangular in shape, with opposed first and second longitudinal sides 56 and 60 and opposed first and second lateral sides 62 and 64. The reaction housing 52 includes outwardly extending tabs or hooks 66 on the first and second longitudinal sides 56 and 60, respectively. As shown in FIG. 2, the cover 54 includes a main panel 70 and a skirt 72 extending therefrom. The cover main panel 70 forms or includes a brim 73, exterior to the skirt 72. Note that the view shown in FIG. 1 is fragmentary in nature as, for example, the cover brim 73 has not there been shown in an effort to facilitate illustration and comprehension. While various forms of covers may be used, the cover 54 is of the form or type commonly referred to as a "clamshell cover" in that such cover normally or commonly forms two separate complementary cover pieces upon opening. The skirt 72 includes a series of windows or slots 74 which mate with the outwardly extending hooks 66 of the reaction housing 52.
While FIG. 1 shows the inclusion of a circular opening 76 in the reaction housing 52 for the placement of an associated inflator device and FIG. 2 includes airbag cushion deployment direction arrows 80 to illustrate the typical deployment directions which an associated airbag cushion will deploy and exert forces onto the assembly, FIGS. 1 and 2 have been simplified by not showing the associated inflator, airbag cushion and associated connection or retention devices or features.
FIGS. 3 and 4 illustrate the module assembly 50 upon actuation and deployment of the associated airbag cushion 82 (shown in FIG. 4 and which FIG. 4 also includes direction arrows 83 illustrating typical or usual direction inflation medium forces upon the airbag cushion 82). As shown in FIGS. 3 and 4, and in accordance with typical such assemblies, upon actuation of the module assembly 50, the airbag cushion 82 acts against the cover 54 such as results in the tearing or otherwise opening of the cover such as to form first and second cover pieces, 84 and 86, respectively, and to permit the airbag cushion 82 to deploy into desired position. Upon such deployment, the outwardly extending housing hooks 66 interact with the cover windows 74 to normally retain the first and second cover pieces 84 and 86 joined to the housing 52 upon deployment.
While the attachment arrangement of U.S. Pat. No. 5,588,669 and such as illustrated in FIGS. 1-4 has generally been successful in overcoming at least some of the problems and shortcomings associated with at least certain of the prior art cover and housing attachment arrangements, further improvements are desired.
For example, as shown in FIGS. 5 and 6, upon the further development of the deployment of the module assembly 50, the deployed airbag cushion 82 may push or rebound against the respective cover 54 (or the pieces 84 and 86 thereof, such as in the event of a clamshell cover), as signified by the arrows 90 in FIG. 6. As a result of the so directed forces, the cover 54 or one or more elements thereof such as the cover pieces 84 and 86 may become dislodged or disengaged from the housing 52, as the outwardly extending housing hooks 66 and the cover windows 74 no longer interact in connecting fashion.
While such a dislodged or disengaged cover element may normally be retained by the restraint system and the occurrence of such dislodgement or disengagement typically does not adversely effect deployment, attachment schemes which avoid such occurrences have been desired.
Thus, there is a need and a demand for an improved airbag module cover attachment arrangement such as may more readily and easily permit or provide positive cover attachment throughout the deployment process (i.e., both during and following deployment including, for example, upon cushion rebound) and do so in a relatively simple, effective and efficient manner. In particular, there is a need and a demand for an improved airbag module cover attachment arrangement which more readily and easily permits or provides positive cover attachment throughout the deployment process without incorporating or relying on the inclusion of one or more of the following features:
Further, in addition to improved attachment arrangements for conventional covers, there is a need and a demand for an improved airbag module cover attachment arrangement such as may more readily permit or facilitate the use of those cover elements designed to tear or otherwise form two or more separate parts upon the occurrence of a deployment event. In particular, there is a need and a demand for an improved such airbag module cover attachment arrangement of simple design and operation wherein each such cover element part is individually retained or remains attached with or to the respective housing even in the event of such cushion rebound.